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氮素是农田土壤的主要养分限制因子之一,在全球气候变化背景下研究农田土壤氮素对温度和降水变化的响应,对评价气候变化农业生态效应具有重要的意义。通过田间试验,利用红外辐射灯管模拟增温,人工减少降水量,并测定土壤氮素含量,以探讨增温和降水减少对冬小麦和大豆生长季土壤氮素的影响规律。试验设置对照(CK)、增温(T,增温约2℃)、降水减少(P,降水量减少30%)、增温和降水减少复合处理(TP,增温约2℃+降水减少30%)4个水平处理。结果表明,在冬小麦生长季,与CK相比,T、P和TP处理显著减少了返青期土壤全氮,增加了成熟期土壤全氮;T和TP处理显著降低了拔节期土壤全氮。T、P和TP处理显著减少了孕穗-抽穗期土壤铵态氮。P和TP处理显著增加了返青-灌浆期土壤硝态氮,T处理显著增加了拔节-抽穗期土壤硝态氮。在大豆生长季,与CK相比,T、P和TP处理对土壤全氮含量的影响都没有达到显著性水平。T处理使鼓粒期土壤铵态氮增加10.0%(P=0.038),T和P处理使结荚期土壤硝态氮分别减少了27.4%(P=0.011)和27.1%(P=0.009),T、P和TP使鼓粒期土壤硝态氮分别增加了46.6%(P=0.007)、41.3%(P=0.014)和56.3%(P=0.003)。研究表明,增温和降水减少改变了农田土壤氮素含量,且对冬小麦生长季土壤氮素的影响较大豆生长季更加明显。
Nitrogen is one of the main nutrients limiting factors of cropland soils. Studying the response of cropland soil nitrogen to temperature and precipitation under the background of global climate change is of great significance for evaluating the agro-ecological effects of climate change. Through field experiments, the use of infrared radiation tube to simulate warming, artificial reduction of precipitation, and determination of soil nitrogen content in order to discuss the effects of warming and precipitation reduction on soil nitrogen in winter wheat and soybean growing season. The experimental set CK, warming (T, warming about 2 ℃), decreasing precipitation (P, decreasing 30% of precipitation), reducing the combination of warming and precipitation (TP, warming about 2 ℃ + decreasing precipitation 30 %) 4 level processing. The results showed that in the growing season of winter wheat, T, P and TP treatments significantly reduced the soil total nitrogen and the soil total nitrogen during maturation stage compared with CK. T and TP treatment significantly decreased soil total nitrogen at jointing stage. T, P and TP treatments significantly reduced soil ammonium nitrogen in booting and heading stages. P and TP treatments significantly increased soil nitrate nitrogen during rejuvenation-filling stage, and T treatment significantly increased soil nitrate nitrogen during jointing-heading stage. In the soybean growing season, the effects of T, P and TP treatment on soil total nitrogen content did not reach significant levels compared with CK. T treatment increased soil ammonium nitrogen by 10.0% (P = 0.038) at the drumming stage and decreased by 27.4% (P = 0.011) and 27.1% (P = 0.009) by T and P treatments, respectively. T, P and TP increased soil NO3 - N by 46.6% (P = 0.007), 41.3% (P = 0.014) and 56.3% (P = 0.003), respectively. The results showed that the decrease of temperature and precipitation changed the soil nitrogen content of farmland, and the effect on soil nitrogen in winter wheat growing season was more obvious than that in soybean growing season.